Recording apparatus and recording method

ABSTRACT

The present invention is applied to a video data recording apparatus having an interface with a computer. The buffer size of a recording buffer  17 A for temporarily storing data and recording the data on a recording medium  18  is switched between a mode for recording data through an interface  24  with a computer and a mode for recording streaming data D 11  such as video data or the like.

TECHNICAL FIELD

The present invention relates to a recording apparatus and a recordingmethod, and can be applied, for example to a video data recordingapparatus having an interface with a computer. According to the presentinvention, the buffer size of a recording buffer for temporarily storingdata and recording the data on a recording medium is switched between amode for recording data through an interface with a computer and a modefor recording streaming data such as video data or the like, therebyreducing the capacity of the buffer memory even if it is arranged to beable to input data to and output data from the computer to increase itsaffinity with the computer.

BACKGROUND ART

Heretofore, video tape recorders combined with cameras are arranged torecord video data that have been produced by imaging a desired subjecton a recording medium which includes a magnetic tape. In recent years,various recording apparatus using disk-shaped recording mediums such ashard disks or the like have been proposed as a replacement for magnetictapes.

There have been available various interfaces that are widely used ininformation processing apparatus such as computers or the like. It hasbeen considered that recording and reproducing apparatus whichincorporate disk-shaped recording mediums such as hard disks or the likemay be simply constructed by using such existing interfaces. Using thoseinterfaces, recording and reproducing apparatus can be simplyconstructed so as to be able to input and output video data to and frompersonal computers, thus allowing the recording and reproducingapparatus to find an increased range of applications.

With the recording and reproducing apparatus being thus arranged,however, a large-capacity buffer memory needs to be provided for thetransfer of data to the recording and reproducing apparatus.

FIG. 1 of the accompanying drawings is a block diagram showing a flow ofvideo data in a recording apparatus for recording video data. In orderto achieve a sufficient level of image quality based on video data thatare compressed by MPEG (Moving Picture Experts Group), it is necessaryto transfer the video data at a rate of about 10 [Mbps]. In thearrangement shown, an encoder 2 outputs video data as streaming data atthe rate of about 10 [Mbps].

A disk-shaped recording medium such as a hard disk or the like recordsthe video data intermittently thereon at a data transfer rate that isabout twice the data transfer rate of the video data output from theencoder 2 because the recording medium 3 needs various processing modesincluding a rotation waiting mode, a seeking mode, and a retrying mode.Therefore, when video data are output as streaming data at the rate of10 [Mbps] from the encoder 2, the video data are transferred to therecording medium 3 at a data transfer rate of 20 [Mbps] at maximum.

The video data are transferred to and from a personal computer (PC) 4through an interface (I/F) 5 according to IEEE (The Institute ofElectrical and Electronics Engineers, Inc.) 1394 or USB (UniversalSerial Bus), and transferred to and from a recording and reproducingapparatus which uses the recording medium 3 through an interface whichincludes an ATAPI (AT Attachment Packet Interface) for performing atrouble-free data exchange with the interface according to IEEE 1394.The recording and reproducing apparatus which uses the recording medium3 requires a buffer memory having a capacity of about 4 [Mbytes] inorder to reduce the frequency of data transfer to and from the personalcomputer 4 connected by the interface 5 for thereby preventing theprocessing efficiency of the personal computer 4 from being lowered. TheATAPI interface has a data transfer rate of 100 [Mbps].

When video data output from the encoder 2 are recorded on the recordingmedium 3, the amount of transferred data varies as shown in FIG. 2 ofthe accompanying drawings in a system buffer 6 that is connected to theencoder 2 and the ATAPI interface and a drive buffer 7 that is connectedto the recording medium 3. In FIG. 2, the data output from the encoder2, the data output from the system buffer 6, and the data output to therecording medium 3 are represented D1, D2, D3, respectively. In FIG. 2,the assembly is in an ideal state where the rotation waiting mode andother modes are ignored in the recording and reproducing apparatus.

When video data start to be recorded (REC Start), compressed video dataD1 are output as streaming data at 10 [Mbps] from the encoder 2 ((A) inFIG. 2). The system buffer 6 and the drive buffer 7 accumulate the videodata D1 and intermittently outputs the accumulated video data D1 ((B) to(E) in FIG. 2). Specifically, when the video data have been accumulatedto a predetermined amount in the system buffer 6 (at time t1), the dataaccumulated in the system buffer 6 are transferred to the drive buffer 7at 100 [Mbps] (in a period from time t1 to time t2), which startrecording the data on the recording medium 3 at 20 [Mbps].

When the amount of data accumulated in the system buffer 6 and the drivebuffer 7 are reduced to a certain level, then the system buffer 6 andthe drive buffer 7 stop sending out the data. This processing sequencewill subsequently be repeated.

If the drive buffer 7 has a storage capacity of 4 [Mbytes], then sincethe drive buffer 7 outputs the video data that are input thereto at thedata transfer rate of 100 [Mbps] to the recording medium 3 at the datatransfer rate of 20 [Mbps], the data transfer rate at which the videodata are input to the drive buffer 7 is greater than the data transferrate at which the video data are output from the drive buffer 7, andhence the video data are progressively accumulated in the drive buffer7. Specifically, in 0.5 [sec.] from time t1, the video data areaccumulated in the drive buffer 7 to the amount of 4 [Mbytes], whereuponno empty storage area is available in the drive buffer 7. At this time,the system buffer 6 needs to stop outputting the video data.

After the video data have started to be recorded until the system buffer6 stops inputting the video data to the drive buffer 7, the systembuffer 6 has recorded 5 [Mbytes] of video data at maximum. Therefore, ifit is assumed that the overall assembly operates in an ideal condition,then the system buffer 6 is required to have a storage capacity of atleast 5 [Mbytes].

FIG. 3 of the accompanying drawings shows a situation in which an errorhas occurred while video data are being recorded on the recording medium3, and the video data stored in the system buffer 6 is to bere-transmitted. Since the system buffer 6 has to store the video data tobe re-transmitted, the system buffer 6 requires a large storagecapacity. In the example shown in FIG. 3, the video data sent from timet1 to time t2 are retried at time t3 or later, and the system buffer 6needs to have a storage capacity of 9 [Mbytes].

Therefore, if the large-capacity drive buffer is employed so as to beable to input data to and output data from the computer for increasedaffinity with the computer, the buffer memory (system memory) forsupplying streaming data to the drive buffer is required to have astorage capacity that is several times greater than the storage capacityof the drive buffer.

DISCLOSURE OF INVENTION

The present invention has been made in view of the above drawbacks, andproposes a recording apparatus and a recording method for reducing thecapacity of a buffer memory even if it is arranged to be able to inputdata to and output data from the computer to increase its affinity withthe computer.

To achieve the above proposal, the present invention is applied to arecording apparatus having an interface connectable to a computer, abuffer memory for temporarily storing and outputting streaming data at adata transfer rate that is relatively lower than the data transfer rateof the interface, and a recording means for temporarily storing dataoutput from the buffer memory and the interface in a recording bufferand recording the data on a recording medium. The recording meansswitches the buffer size of the recording buffer between a mode forrecording the data output from the interface on the recording medium anda mode for recording the data output from the buffer memory on therecording medium.

With the arrangement of the present invention, since the invention isapplied to a recording apparatus having an interface connectable to acomputer, a buffer memory for temporarily storing and outputtingstreaming data at a data transfer rate that is relatively lower than thedata transfer rate of the interface, and a recording means fortemporarily storing data output from the buffer memory and the interfacein a recording buffer and recording the data on a recording medium, theinvention is applicable to a recording apparatus combined with a camera,which is connectable to a computer and serves to record stream dataincluding video data acquired by an imaging means on a recording mediumsuch as a hard disk, an optical disk, or the like. In the abovearrangement, the buffer memory for the streaming data is required toresend streaming data stored in the recording buffer in response to aresending request. According to the present invention, the recordingmeans switches the buffer size of the recording buffer between the modefor recording the data output from the interface on the recording mediumand the mode for recording the data output from the buffer memory on therecording medium. For recording the streaming data, the buffer size ofthe recording buffer is set to a smaller size to reduce the amount ofstreaming data to be resent from the buffer memory in response to aresending request. The buffer memory for the streaming data may thushave a storage capacity that is reduced accordingly.

The present invention is also applicable to recording method oftemporarily storing streaming data at a data transfer rate that isrelatively lower than the data transfer rate of an interface connectableto a computer, in a recording buffer and recording the streaming data ona recording medium, characterized by switching the buffer size of therecording buffer between a mode for recording the data output from theinterface on the recording medium and a mode for recording the dataoutput from the buffer memory on the recording medium.

With the arrangement of the present invention, the recording methodallows the buffer memory for the streaming data to have a reducedstorage capacity.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram of an arrangement of a recording apparatus towhich a computer can be connected;

FIG. 2 is a timing chart showing how the amount of data varies inbuffers in the recording apparatus shown in FIG. 1;

FIG. 3 is a timing chart showing how the amount of data varies in thebuffers when an error has occurred;

FIG. 4 is a block diagram of a recording apparatus according to anembodiment of the present invention;

FIG. 5 is a block diagram showing flows of data in a recording mode inthe recording apparatus shown in FIG. 4.

FIG. 6 is a block diagram showing flows of data in a reproduction modein the recording apparatus shown in FIG. 4;

FIG. 7 is a block diagram illustrative of the manner in which data areinput and output between the recording apparatus shown in FIG. 4 and acomputer;

FIG. 8 is a flowchart of a processing sequence of a drive block in therecording apparatus shown in FIG. 4;

FIG. 9 is a timing chart showing how the amount of data varies inbuffers in the recording apparatus shown in FIG. 4; and

FIG. 10 is a timing chart showing how the amount of data varies in thebuffers when an error has occurred.

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will be described in detail belowwith reference to the drawings.

(1) Arrangement of the Embodiment

FIG. 4 is a block diagram of a recording apparatus according to anembodiment of the present invention. The recording apparatus is aportable recording apparatus combined with a camera, including arecording and reproducing system which employs a hard disk drive, ratherthan a recording and reproducing system which employs a magnetic tape ina conventional video tape recorder combined with a camera.

In the recording apparatus 11, a camera 12 images of a desired subjectthrough a lens and outputs video data of the captured image. A videoencoder 13 compresses the video data produced by the camera 12 in aformat of MPEG, for example, and outputs the compressed video data. Amicrophone 14 picks up an audio signal, amplifies the audio signal, andoutputs the audio signal as a digital signal. An audio encoder 15compresses the digital audio signal and outputs the compressed audiosignal.

In a mode for recording the captured image, a system block 16 processesthe video data output from the video encoder 13 and the audio dataoutput from the audio encoder 15 according to a time-divisionmultiplexing process. The system block 16 generates streaming data at 10[Mbps] according to the time-division multiplexing process, and outputsthe streaming data via a system buffer 16A to a drive block 17. Thesystem block 16 also outputs the video data from the camera 12 and theaudio data from the microphone 14 directly to a display 19, an audioprocessor 20, and line outputs for monitoring purposes. In a mode forreproducing the recorded captured image, the system block 16 receivesreproduced data from the drive block 17 via the system buffer 16A,separates the reproduced data into video data and audio data, andoutputs the video data and the audio data respectively to a videodecoder 21 and an audio decoder 22.

For simply monitoring the captured image, the system block 16 outputsthe video data from the camera 12 and the audio data from the microphone14 to the display 19, the audio processor 20, and the line outputs. Inthe above processes, the system block 16 responds to control actions ofthe user and outputs various commands to various parts of the driveblock 17, and so forth for thereby controlling the overall operation ofthe recording apparatus 11.

In the reproducing mode, the video decoder 21 expands the video dataoutput from the system block 16 and outputs the expanded video data tothe display 19 and the line output. In the reproducing mode, the audiodecoder 22 expands the audio data output from the system block 16 andoutputs the expanded audio data to the audio processor 20 and the lineoutput.

For monitoring the captured image, the display 19 activates aliquid-crystal display panel with the video data output from the systemblock 16 for thereby displaying a monitor image of the captured image.In the reproducing mode, the display 19 activates the liquid-crystaldisplay panel with the video data output from the video decoder 21 forthereby displaying a monitor image of the reproduced image. Formonitoring the captured image, the audio processor 20 activates speakersor the like with the audio data output from the system block 16 forthereby outputting a monitor audio signal. In the reproducing mode, theaudio processor 20 activates the speakers or the like with the audiodata output from the audio decoder 22 for thereby outputting a monitoraudio signal of the reproduced sound.

The drive block 17 and a hard disk 18 jointly make up a hard disk drive,and records the data output from the system block 16 on the hard disk18. The drive block 17 also reproduces the data recorded on the harddisk 18 and outputs the reproduced data to an interface (I/F) 24. Thedrive block 17 transfers the data at a data transfer rate of 20 [Mbps]to record the data on and reproduced the data from the hard disk 18.

As shown in FIG. 5, in the recording apparatus 11, the video data fromthe camera 12 and the audio data from the microphone 14 are compressedby the video encoder 13 and the audio encoder 15, respectively, thecompressed data are processed by the system block 16 according to thetime-division multiplexing process, and the resultant streaming data arerecorded on the hard disk 18. Concurrent with the above processing, thesystem block 16 inputs the video data from the camera 12 and the audiodata from the microphone 14 to the display 19 and the audio processor20, respectively, and outputs them from the line outputs for monitoringthe captured data.

In the reproducing mode, as shown in FIG. 16, the drive block 17 inputsthe reproduced data from the hard disk 18 to the system block 16, whichdivides the data into video data and audio data that are expandedrespectively by the video decoder 21 and the audio decoder 22. Theexpanded video data and audio data can be confirmed by the display 19and the audio processor 20 and also by an external device.

The interface (I/F) 24 includes an interface according to IEEE 1394,USB, or the like, and outputs the data output from the drive block 17 toan external device such as a personal computer (PC) or the like.

As shown in FIG. 7, in the recording apparatus 11, the personal computeroutputs various commands through the drive block 17 and the interface 24to the drive block 17 for thereby controlling operation of the hard diskdrive to record various data from the personal computer on the hard disk18 and acquire data recorded on the hard disk 18 at the personalcomputer.

According to the present embodiment, in the recording apparatus 11, thesystem block 16, the drive block 17, and the interface 24 are connectedby an ATAPI for transferring data therebetween at a data transfer rateof 100 [Mbps]. The drive block 17 has a drive buffer 17A of 4 [Mbytes].A controller for controlling operation of the drive block 17 performs aprocessing sequence shown in FIG. 8 to switch between buffer sizes ofthe drive buffer 17A from a data input destination, so that the systembuffer 16A may include a small-capacity memory.

Specifically, when a command for instructing the recording of data onthe hard disk 18 is input through the ATAPI to the controller for thedrive block 17, control goes from step SP1 to step SP2, which determineswhether or not the data are to be recorded in the connected computer,i.e., whether or not the data are to be recorded through the interface24, depending on an input destination for the data to be recorded.

If the answer is affirmative, then control goes from step SP2 to stepSP3 in which the buffer size of the drive buffer 17A is set to 4[Mbytes], after which control goes to step SP4 to return to the originalprocessing sequence. Conversely, if the answer is negative in step SP2,then control goes from step SP2 to step SP5 in which the buffer size ofthe drive buffer 17A is set to 0.5 [Mbyte], after which control goes tostep SP4 to return to the original processing sequence.

In the recording apparatus 11, therefore, for recording streaming data,the amount of streaming data to be sent again from the system buffer 16Ato the drive buffer 17A upon a resending request is reduced by theamount by which the buffer size of the drive buffer 17A is reduced.Thus, the capacity of the system buffer 16A is also reduced.

According to the present embodiment, the interface 24 includes aninterface connectable to the computer, and the system buffer 16Aincludes a buffer memory for temporarily storing and outputtingstreaming data at a data transfer rate that is relatively lower than thedata transfer rate of the interface 24. The drive block 17 includes arecording means for temporarily storing data output from the buffermemory for streaming data and the interface in the drive buffer 17A thatserves as a recording buffer, and recording the data on the hard disk18.

(2) Operation of the Embodiment

With the above arrangement, in the recording medium 11 (FIGS. 4 and 5),video data representing a captured image and audio data from a subjectare acquired from the camera 12 and the microphone 14, respectively, andthe video data and the audio data are supplied through the system block16 to the display 19 and the audio processor 20, respectively, formonitoring the captured image and the sound of the subject.

For recording the captured result on the hard disk 18, a command fromthe system block 16 is transmitted through the ATAPI interface to thedrive block 17 to cause the hard disk drive to switch operation modes.Then, the video data and the audio data output respectively from thecamera 12 and the microphone 14 are compressed respectively by the videoencoder 13 and the audio encoder 15. Thereafter, the video data and theaudio data are processed by the system block 16 according to thetime-division multiplexing process, generating streaming data. Thestreaming data are transmitted through the system buffer 16A and theATAPI interface to the drive block 17. The drive block 17 records thetransmitted data through the drive buffer 17A on the hard disk 18 (FIG.5).

In the reproducing mode (FIG. 6), a command from the system block 16causes the drive block 17 to switch its operation modes to reproducedata from the hard disk 18. The reproduced data are input through thedrive buffer 17A to the system block 16, which divides the data intovideo data and audio data that are expanded respectively by the videodecoder 21 and the audio decoder 22. The expanded video data and audiodata are output to the display 19 and the audio processor 20,respectively.

When the personal computer is to access the hard disk 18 (FIG. 7), thepersonal computer supplies a command through the interface 24 to thedrive block 17, which switches its operation modes. For recording datafrom the personal computer on the hard disk 18, the corresponding dataare output from the personal computer by a response from the drive block17, input through the interface 24 to the drive block 17, and recordedon the hard disk 18 by the drive block 17. Conversely, for reproducingdata recorded on the hard disk 18 and outputting the data to thepersonal computer, the reproduced data produced when the hard disk 18 isplayed back are output through the drive block 17 and the interface 24to the personal computer.

While in a data exchange with the personal computer (FIG. 4), in therecording apparatus 11, data input from the interface 24 are temporarilyaccumulated in the drive buffer 17A and recorded on the hard disk 18,and reproduced data from the hard disk 18 are temporarily accumulated inthe drive buffer 17A and output to the personal computer. The driveblock 17 makes a decision to set the buffer size of the drive buffer 17Ato a larger capacity of 4 [Mbps] (FIG. 8).

After outputting commands for recording or reproducing data, thepersonal computer sends data to the recording apparatus 11 at a highrate based on a response from the drive block 17, and thereafter canperform another process. Conversely, until a sufficient amount ofreproduced data is accumulated in the recording apparatus 11, thepersonal computer can perform another process, and can acquire thereproduced data from the recording apparatus 11 between such otherprocesses. The recording apparatus 11 can thus send data to and receivedata from the computer, can prevent frequent access from the computer,and can have a high affinity with the computer.

For recording streaming data representative of the captured result, thebuffer size of the drive buffer 17A is set to 0.5 [Mbytes], thusreducing a capacity required by the system buffer 16A.

As shown in FIG. 9 in comparison with FIG. 2, for recording streamingdata on the hard disk 18 through the drive buffer 17A at times t1, t3,t5 when the buffer size of the drive buffer 17A is set to 0.5 [Mbytes]and the amount of data in the system buffer 16A is increased to 5[Mbytes], immediately after the data have started being transferred fromthe system buffer 16A at time t1, since there is an empty storage areaavailable in the drive buffer 17A, the streaming data are transferredfrom the system buffer 16A to the drive buffer 17A at a data transferrate of 100 [Mbps].

The drive buffer 17A records the streaming data thus transferred on thehard disk 18. Since the data streaming data are recorded at a datatransfer rate of 20 [Mbps], the drive buffer 17A immediately suffers alack of empty storage area. The drive block 17 instructs the systemblock 16 to wait for transferring data through the ATAPI interface. Whenan empty storage area becomes available in the drive buffer 17A as dataare recorded on the hard disk 18, the drive block 17 permits the systemblock 16 to transfer streaming data.

Thus, in the system buffer 16A, the data transfer rate for the driveblock 17 is limited to 20 [Mbps] which is the rate at which data arerecorded on the hard disk 18. The drive buffer 17A stores streaming dataat 0.5 [Mbps].

As shown in FIG. 10 in comparison with FIG. 3, if a resending request isissued from the drive block 17 for streaming data that are sent at timet1, for example, then the system block 16 may resend as much streamingdata as stored by the drive block 17, and hence may have acorrespondingly reduced storage area required for storing streaming datato be resent. Specifically, as can be seen from a comparison with FIG.3, the system buffer 16A may have a storage capacity of 5.5. [Mbytes].

According to the present embodiment, therefore, the system buffer 16Ahas a reduced storage capacity, and hence the overall arrangement of theapparatus may be simplified accordingly.

(3) Effects of the Embodiment

With the above arrangement, the buffer size of a recording buffer fortemporarily storing data and recording the data on a recording medium isswitched between a mode for recording data through an interface with acomputer and a mode for recording streaming data such as video data orthe like, thereby reducing the capacity of the buffer memory even if itis arranged to be able to input data to and output data from thecomputer to increase its affinity with the computer.

The system block is thus simplified in structure, and, if it isimplemented as an integrated circuit, the chip has a reduced area.

(4) Other Embodiments

In the above embodiment, streaming data produced by processingcompressed video data and compressed audio data according to atime-division multiplexing process are recorded. The present inventionis not limited to the recording such streaming data, but may be appliedto a wide range of applications including the recording of uncompressedvideo data, the recording of audio data, and so forth.

In the above embodiment, the captured image and sound from the subjectare recorded. However, the present invention is not limited to therecording of such data, but may be applied to a wide range ofapplications including the recording of video data or the like suppliedfrom a line input.

In the above embodiment, the interfaces according to ATAPI, IEEE 1394,and so forth are employed. However, the present invention is not limitedto those interfaces, but may be applied to a wide range of applicationsincluding various interfaces, if necessary.

In the above embodiments, streaming data are recorded by the hard diskdrive. However, the present invention is not limited to the recording ofdata with the hard disk drive, but may be applied to a wide range ofapplications including the recording of data with an optical disk drive,a memory card, and so forth.

According to the present invention, as described above, the buffer sizeof a recording buffer for temporarily storing data and recording thedata on a recording medium is switched between a mode for recording datathrough an interface with a computer and a mode for recording streamingdata such as video data or the like, thereby reducing the capacity ofthe buffer memory even if it is arranged to be able to input data to andoutput data from the computer to increase its affinity with thecomputer.

INDUSTRIAL APPLICABILITY

The present invention relates to a recording apparatus and a recordingmethod, and can be applied to a video data recording apparatus having aninterface with a computer.

1-3. (canceled)
 4. An imaging apparatus, comprising: imaging means forimaging an object; an interface connectable to an external computer; abuffer memory for temporarily storing and outputting streaming data fromsaid imaging means at a data transfer rate that is lower than a datatransfer rate of said interface; recording means for temporarily storingdata output from said buffer memory and said interface in a recordingbuffer and recording the data on a recording medium; a detecting meansfor detecting a connection with the external computer through theinterface; wherein said recording means switches the buffer size of saidrecording buffer based on detection of the connection with the externalcomputer.
 5. The imaging apparatus of claim 4, wherein the buffer sizeof the recording buffer is bigger when the external computer isconnected than when the external computer is not connected.
 6. A methodof recording an image, comprising: imaging an object; enabling aconnection to receive data from an external computer through aninterface; storing and outputting streaming data at a data transfer ratethat is lower than a data transfer rate of said interface; storing saidoutput streaming data and data from said interface in a recording bufferand recording the data on a recording medium; a detecting means fordetecting a connection with the external computer through the interface;wherein said recording means switches the buffer size of said recordingbuffer based on detection of the connection with the external computer.7. The imaging apparatus of claim 4, wherein the buffer size of therecording buffer is bigger when the external computer is connected thanwhen the external computer is not connected.